Black liberals keep bemoaning the danger to their own teenage sons after the "not guilty" verdict in George Zimmerman's murder trial. To avoid what happened to Trayvon Martin, their boys need only follow this advice: Don't walk up to a stranger and punch him, ground-and-pound him, MMA-style, and repeatedly smash his head against the pavement.

The Justice-for-Trayvon crowd keeps pretending there hasn't been a trial where the evidence overwhelmingly showed that Trayvon committed the first (and only) crime that night by assaulting Zimmerman. Instead, the race agitators are sticking with the original story peddled by the media, back when we had zero facts. To wit, that Zimmerman had stalked a young black child and shot him dead just for being black and wearing a hoodie.

Dozens of these hair-on-fire racism stories are retold in my book, "Mugged: Racial Demagoguery From the Seventies to Obama." In the golden age of racial demagoguery, they came at a pace of about one a year. Al Sharpton was usually involved.

A normal person would hear some of the more outlandish allegations and think, "I can't believe it!" not meaning, "Wow! What a blockbuster story!" but rather, "I would like to hear the facts because I literally don't believe it." (That was much of America's reaction to the media's claim last year that a neighborhood-watch captain in Florida had hunted down a black teenager and shot him dead just for wearing a hoodie.)

Whenever a much-celebrated claim of racism turned out to be false -- which was almost always -- you'd just stop hearing about it. There would never be a clippable story admitting that the media's harrumphing had been in error: Attention, readers! That story we've been howling about for several months turned out to be a complete fraud.

A little time would pass, and then we'd get an all-new, excited "America is still racist" media campaign. Journalists are incapable of learning that they should get all the facts before launching moral crusades.

As a result, the official record shows: A few hate crimes and some unverified hate crimes with no clear resolution one way or another. As long as the fraudulent hate crimes didn't get counted as strikeouts, liberals always looked like Ted Williams.

Since they didn't keep an accurate batting average, I did it for them in "Mugged."

The case most like George Zimmerman's is the Edmund Perry case. In 1985, Perry, a black teenager from Harlem who had just graduated from Phillips Exeter Academy, mugged a guy who turned out to be an undercover cop. He got shot and a few hours later was dead.

Instead of waiting for the facts, the media rushed out with a story about Officer Lee Van Houten being a trigger-happy, racist cop. When that turned out to be false, The New York Times looked at its shoes. It was the kind of story the elites wanted to be true. It should be true. We had such high hopes for that one. Damn!

The initial news accounts stressed not only that Perry was a graduate of Exeter on his way to Stanford, but that he was unarmed. (In all white-on-black shootings, the media expect the white to have RoboCop-like superpowers to detect any weapons on the perp as well as his resume.)

A few weeks after the shooting, The New York Times called Perry "a prized symbol of hope." In a telling bit of obtuseness, The Times said that "all New Yorkers have extraordinary reasons to wish for the innocence of the young man who was killed." I doubt very much that the cop being accused of being a murderous racist hoped for that.

An article in The Village Voice explained: "[L]ike so many other victims in this city," Perry was "just too black for his own good."

Luckily for the policeman, Perry had mugged him in a well-lit hospital parking lot. Twenty-three witnesses backed the officer's story in testimony to the grand jury. (Unlike Zimmerman, Van Houten's case was at least presented to a grand jury.)

As I wrote in "Mugged": "God help Officer Van Houten if he had been mugged someplace other than a hospital parking lot with plenty of witnesses." Such as, for example, a dark pathway in The Retreat at Twin Lakes. There weren't 23 witnesses backing Zimmerman's story, only about a half-dozen. But, as with Van Houten, the evidence overwhelmingly corroborated Zimmerman's story.

In Van Houten's case, even after it was blindingly clear that Perry had mugged him, the truth was only revealed amid great sorrow. When the facts were unknown, the cop was a racist. When it turned out Perry had mugged the cop, it was no one's fault, but a problem of "violence," "confusion" and "two worlds" colliding.

Perhaps, someday, blacks will win the right to be treated like volitional human beings. But not yet.

As with Zimmerman's case this week, some journalists pretended to have missed the court proceedings that supported the self-defense story. Even after the grand jury's refusal to indict Van Houten, Dorothy J. Gaiter of the Miami Herald wrote about Perry in an article titled "To Be Black and Male Is Dangerous in U.S." She asked: "How do you teach a boy to be a man in a society where others may view him as a threat just because he is black?"

Van Houten said he was jumped, knocked to the ground, punched and kicked by Edmund Perry. Grand jury witnesses backed his story. Isn't it possible that Van Houten saw Perry as a threat for reasons other than "just because he is black"?

(And please stop talking about Martin's "hoodie"! Zimmerman wasn't worried about the hoodie; he was worried about being beaten to death.)
Instead of turning every story about a black person killed by a white person into an occasion to announce, "The simple fact is, America is a racist society," liberals might, one time, ask the question: Why do you suppose there would be a generalized fear of young black males? What might that be based on?

Throw us a bone. It's because a disproportionate number of criminals are young black males. It just happens that when Lee Van Houten and George Zimmerman were mugged by two of them, they survived the encounter.